As a method of peptide synthesis, besides a solid phase method and a liquid phase method, a production method using a protecting group (hereinafter to be also referred to as anchor), comprising performing a reaction in a homogeneous liquid phase, changing the solvent composition after the reaction, and isolating and purifying the reaction mixture only by filtration and washing has recently been proposed.
Patent document 1 and non-patent document 1 each disclose a method comprising using a 3,4,5-tris(n-octadecyloxy)benzyl alcohol type compound as a protecting reagent of a carboxyl group and the like. However, an alkylation suppressive effect on removal of the protecting group is not described at all.
Patent documents 2-4 each disclose protecting reagents such as a 3,5-di(docosyloxy)benzyl alcohol type compound, a 2,4-di(docosyloxy)benzyl alcohol type compound and the like. However, an alkylation suppressive effect on removal of the protecting group is not described at all.
Patent document 4 also discloses a protecting reagent of a trityl type. However, the protecting group is not entirely satisfactory as an anchor since a side reaction such as dissociation thereof even in methanol and the like occur.